LAUSR

Abstract Flue gas recirculation (FGR) has been widely adopted as the steam temperature regulation method of choice for double-reheat boilers. In this work, the effect of the FGR position on the hydrodynamic characteristics of a double-reheat boiler is studied. Heat flux distributions of the water-cooled wall are determined through combustion simulation, then hydrodynamic characteristics of the boiler are calculated by user-defined program. The hydrodynamic characteristics including working fluid temperature, average tube temperature, fin-tip temperature, and temperature deviation between adjacent loops under 100% boiler maximum continuous rating (BMCR) and 75% turbine heat acceptance (THA) loads were numerically analyzed. The calculation results show that, under 100% BMCR and 75% THA loads, compared with the case that FGR introduced from the nozzle above the burner, the average tube and fin-tip temperatures at the outlet of water-cooled wall are higher, and the temperature deviation between adjacent loops is more significant, when the FGR is introduced from the nozzle below the burner. Therefore, it is suggested in this work that introducing FGR from the nozzle above the burner is safer for water-cooled walls of the 1000 MW double-reheat boiler.